Gale Warning 132, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
331 PM AKST WED FEB 16 2011

.SHORT TERM...LOW PRESSURE NEAR THE BRITISH COLUMBIA COAST TO
DIXON ENTRANCE WITH AN INVERTED THROUGH TOWARDS PRINCE WILLIAM
SOUND PERSISTING AND SLOWLY WEAKENING. THERE IS AN AREA OF HIGH
PRESSURE OVER NORTHWEST CANADA THAT IS BUILDING SLIGHTLY THROUGH
TONIGHT BEFORE DRIFTING TO THE SE. TIGHT PRESSURE GRADIENTS
THROUGH INTERIOR PASSES TONIGHT AND EARLY THU AS THE HIGH MOVES
OFF. GALE FORCE WINDS FOR A LARGE CHUNK OF THE INNER CHANNELS.
COLD TEMPERATURE HAVE LOCAL AREAS OF COLD WIND CHILLS MAINLY
WHITE PASS REGION THOUGH. FREEZING SPRAY AND HEAVY FREEZING
SPRAY...FOR THE NORTHERN THIRD MARINE ZONES.

FOR THE FORECAST UPDATES I WENT WITH A NAM AND WRF COMBO FOR
WINDS AND NAM FOR MOST OF THE REST OF THE FORECAST. BASICALLY DUE
TO THE WAY THE PRESSURE GRADIENT WAS STACKED ALONG THE MOUNTAINS.
A FEW FLURRIES OVER SOUTHERN BUT NO REAL ACCUMULATIONS.

EXTENDED THE WINTER WEATHER ADVISORY FOR THE WHITE PASS THROUGH
THU AFTERNOON. WILL BE ISSUING FOR INTERIOR PASSES FOR MAINLY
STIKINE VALLEY AND THE BEHM CANAL AND PORTLAND CANAL AREAS.

&&

.LONG TERM...UPPER LEVEL RIDGE IN EASTERN GULF AND SURFACE HIGH
OVER THE YUKON WILL MOVE OFF TO THE SE THURSDAY NIGHT. THIS ALLOWS
A SHORTWAVE TROUGH OVER THE INTERIOR TO DIG SE INTO GULF FRIDAY.
SURFACE LOW TRACKS EAST ACROSS SOUTHERN ALASKA WITH A SECONDARY
LOW DEVELOPING IN NORTH CENTRAL GULF FRIDAY NIGHT. THIS LOW THEN
TRACKS SE ALONG THE OUTER COAST SATURDAY. A NEW ARCTIC HIGH BUILDS
INTO THE YUKON THROUGH EARLY NEXT WEEK WITH A MARITIME HIGH
SETTING UP OVER THE NORTH CENTRAL PACIFIC. THIS WILL ALLOW A
SERIES OF WEEK FAST MOVING LOWS TO DIG SE THROUGH THE EASTERN GULF
LATE IN THE LONG TERM PERIOD.

GENERALLY CLEAR BUT NOT AS COLD OR WINDY THURSDAY NIGHT WITH
OVERALL GRADIENT WEAKENING AND FLOW ALOFT TURNING WESTERLY.

A WARM FRONT WILL MOVE INTO EASTERN GULF FRIDAY WITH OVERRUNNING
SNOW BEGINNING IN PAYA AND POSSIBLY AS FAR SOUTH AS PAEL. WARM
FRONT MOVES ALOFT OVER SOUTHEAST ALASKA FRIDAY NIGHT WITH PCPN
RATES INCREASING AND POSSIBLY COULD SEE HEAVY SNOW ACROSS COASTAL
AND CENTRAL AREAS LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING.
CURRENT GRIDS SUGGEST 6 TO 9 INCHES IN AN 18 HR PERIOD SO WILL
NEED AN ADVISORY TO POSSIBLE WARNING. SNOW SPREADS TO SOUTH CENTRAL
AND SOUTHERN AREAS BY SATURDAY MORNING. WITH LOW IN THE INTERIOR
WILL SEE GRADIENT FLIP TO A SOUTHERLY SMCR FOR A SHORT WHILE
FRIDAY NIGHT. THIS COULD PUSH TEMPS ALONG THE COAST AND OVER
SOUTHERN TO JUST ABOVE FREEZING AND MAY SEE SOME MIXED PRCP BUT
THINK MAINLY SNOW.

A MODERATE WESTERLY OVER THE GULF WILL BUILD SEAS FRIDAY AND COULD
BE IN 15 TO 20 FOOT RANGE ON SAT. AS HIGH BUILD BACK INTO YUKON
SAT NIGHT AND SUNDAY WILL SEE A RETURN OF NORTHERLY WINDS WHICH
INCREASE TO GALE FORCE ON MON-TUE WITH RENEWED CAA.

2 MORE SIMILAR SYSTEMS FOLLOW MID AND LATE WEEK.

DECENT AGREEMENT THROUGH SAT ALTHOUGH THERE IS A TIMING DIFFERENCE
WITH GFS FASTER VS SLOWER EC. NAM HAD MIDDLE GROUND AND WAS USED
THROUGH DAY 3.5 AND A HPC/GFS/EC BLEND FOR LONGER RANGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM AKST THURSDAY FOR
     AKZ026.
         WIND ADVISORY UNTIL 3 PM AKST THURSDAY FOR AKZ025.
         WINTER WEATHER ADVISORY UNTIL 4 PM AKST THURSDAY FOR AKZ018.
         WIND ADVISORY FROM 3 AM TO 3 PM AKST THURSDAY FOR AKZ029.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ013-031.
         HEAVY FREEZING SPRAY WARNING FOR PKZ011-012.
         GALE WARNING FOR PKZ011>013-022-031-042-043.
         SMALL CRAFT ADVISORY FOR PKZ021-032>036-041-051.

&&

BEZENEK/MM